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270 Wby mag bullet performance

19 Jul 2013
@ 08:48 pm (GMT)

Arve Ringsbye

Changing hunting bullet in my 270 Wby from 150 gr Hornady interlock. The two last seasons i've shot the mentioned interlock which have performed very well, last shot on a red deer bull at 360 meters, weight 130 kg, drt. This hunting season I want to be able to shoot cross canion, from my preplanned post thats 550 - 600 meters at most.

I've utilised the 150 gr SST, but before my fine tuning was finished there where no more bullets to by here in Norway. Midway.no tells me that there are import restrictions because of new US regulations??

Anyway I decided to test the 160 gr partition. So far I've got 15mm groups at 100m with; H1000, 73gr, mv 3120, coal 3.28 and 10 -15mm groups with V N560, 68,5gr, mv 3100, coal 3,30.

Bullet run out all loads < 0,002.

I'm not finished fine tuning the loads, so have not decided upon which powder to use.

My question is - will the 160 gr partition perform at those distances, and what to expect from it, and what will be on the weak side with this bullet when hunting deer 100 - 180 kg at 500 - 600 meters?

Best regards from Norway!

Replies

20 Jul 2013
@ 05:24 pm (GMT)

Quote this

Nathan Foster

Re: 270 Wby mag bullet performance

Hi Arve, great to hear from you, been a while.

If you go to the wound data base on this site, you will find a 160gr .270 Partition autopsy. The bullet worked exceptionally well. The only downside of the 160gr is that its semi point design limits BC, the loss in velocity lowering the effective range to a degree. In my tests, the Partition is most spectacular at impact velocities of 2200fps and above, but it is capable of producing very clean killing (and sometimes continuing to remain dramatic) out to 1800fps. Beyond this velocity paramater, performance drops off rapidly, the Partition unable to shed enough weight to effect disproportionate to caliber wounding.

160gr Partition semi point BC .434 (not unlike 130gr BTSP .270 bullets)

From 3100fps, 2200fps is breached at around 435 yards or 400 meters, 1800fps at around 660 yards or 600 meters. This pretty much covers your estimated needs.

The 150 grain Partition has a higher BC of .465. This bullet breaks 1800fps at around 755 yards or 690 meters. Not a huge difference, but is there if you need it.

Hopefully the 160 grain bullet will meet ideal body weight resistance on the Red deer you mentioned. If you find that you are encountering lean animals or that ranges are longer than anticipated, then you may want to switch to the lighter bullet if stocks are available.

Keep your camera handy Arve!